Host devices such as computers, laptops, personal video recorders (PVRs), MP3 players, game consoles, servers, set-top boxes, digital cameras, and/or other electronic devices often need to store a large amount of data. Storage devices such as hard disk drives (HDD) may be used to meet these storage requirements.
Referring now to FIG. 1, an exemplary hard disk drive (HDD) 10 is shown to include a hard disk drive (HDD) system on chip (SOC) 12 and a hard drive assembly (HDA) 13. The HDA 13 includes one or more hard drive platters 14 that are coated with magnetic layers 15. The magnetic layers 15 store positive and negative magnetic fields that represent binary 1's and 0's. A spindle motor, which is shown schematically at 16, rotates the hard drive platter 14. Generally the spindle motor 16 rotates the hard drive platter 14 at a fixed speed during read/write operations. One or more read/write actuator arms 18 move relative to the hard drive platter 14 to read and/or write data to/from the hard drive platters 14.
A read/write device 20 is located near a distal end of the read/write arm 18. The read/write device 20 includes a write element such as an inductor that generates a magnetic field. The read/write device 20 also includes a read element (such as a magneto-resistive (MR) element) that senses the magnetic field on the platter 14. A preamp circuit 22 amplifies analog read/write signals.
When reading data, the preamp circuit 22 amplifies low level signals from the read element and outputs the amplified signal to a read/write channel device 24. When writing data, a write current is generated which flows through the write element of the read/write device 20. The write current is switched to produce a magnetic field having a positive or negative polarity. The positive or negative polarity is stored by the hard drive platter 14 and is used to represent data.
The HDD SOC 12 typically includes a buffer 32 that stores data that is associated with the control of the hard disk drive and/or buffers data to allow data to be collected and transmitted as larger data blocks to improve efficiency. The buffer 32 may employ DRAM, SDRAM or other types of low latency memory. The HDD SOC 12 further includes a processor 34 that performs processing that is related to the operation of the HDD 10.
The HDD SOC 12 further includes a hard disk controller (HDC) 36 that communicates with a host device via an input/output (I/O) interface 38. The HDC 36 also communicates with a spindle/voice coil motor (VCM) driver 40 and/or the read/write channel device 24. The I/O interface 38 can be a serial or parallel interface, such as an Integrated Drive Electronics (IDE), Advanced Technology Attachment (ATA), or serial ATA (SATA) interface. The spindle/VCM driver 40 controls the spindle motor 16, which rotates the platter 14. The spindle/VCM driver 40 also generates control signals that position the read/write arm 18, for example using a voice coil actuator, a stepper motor or any other suitable actuator. The I/O interface 38 communicates with an I/O interface 44 that is associated with a host device 46.
Referring now to FIG. 2, an exemplary host device 64 is shown to include a processor 66 with memory 67 such as cache. The processor 66 communicates with an input/output (I/O) interface 68. Volatile memory 69 such as random access memory (RAM) 70 and/or other suitable electronic data storage also communicates with the interface 68. A graphics processor 71 and memory 72 such as cache increase the speed of graphics processing and performance.
One or more I/O devices such as a keyboard 73 and a pointing device 74 (such as a mouse and/or other suitable device) communicate with the interface 68. The computer architecture 64 may also include a display 76, an audio output device 77 such as audio speakers and/or other input/output devices that are generally identified at 78.
In use, the HDD is operated independently from the host device. The hard disk drive handles buffering of data locally to improve performance. This approach requires the hard disk drive to include low latency RAM such as DRAM, which increases the cost of the hard disk drive.
Referring now to FIG. 3, a desktop HDD SOC 200 for a host device such as a desktop computer is shown. The HDD SOC 200 includes a processor 204, a hard disk controller (HDC) 208, a read/write channel circuit 212, memory 216 (which can be implemented on chip and/or off chip), and a high speed interface 220. For example, the high speed interface 220 can be a serial or parallel interface such as an ATA and/or SATA interface that communicates with a host device 224. In this embodiment, the spindle/VCM driver is shown integrated with the processor 204. The HDA 13 interfaces with the processor 204 and the read/write channel circuit 212. A host device 226 includes an ATA/SATA interface 228, which communicates with the ATA/SATA interface 220. Operation of the HDD SOC 220 is similar to that described above in conjunction with FIG. 1.
Referring now to FIG. 4, an enterprise HDD SOC 230 for an enterprise device 232 such as a server or other enterprise devices is shown. The HDD SOC 230 includes a spindle/VCM/Data processor 234 that performs processing related to the spindle motor, VCM and/or data processing. The HDD SOC 230 further includes an interface/data processor 236 that performs processing related to the enterprise device interface. The HDD SOC 230 also includes a hard disk controller (HDC) 238, a read/write channel circuit 242, memory 246 (which can be implemented on chip) and a high speed interface 250. For example, the high speed interface 250 can be a serial or parallel interface such as a small computer system interface (SCSI), serial attached SCSI (SAS) or Fiber Channel (FC) interface that communicates with the enterprise device 232 via a high speed interface 251.
Because of the different number of processors and the different output side interfaces that are used, manufacturers have designed and manufactured two different HDD SOC architectures for enterprise and desktop applications. In particular, the desktop HDD SOC 200 includes a single processor while the enterprise HDD SOC 230 includes two processors. In addition, the desktop HDD SOC 200 typically employs an ATA and/or SATA interface while the enterprise server typically employs an SAS and/or FC interface. The separate architectures increase the design inventory and die costs of both devices.